Automatic focusing device for copying cameras, projectors, and the like



April 13, 1937- R. H. DRAEGER ET AL AUTOMATIC FOCUSING DEVICE FORCOPYING CAMERAS, PROJECTORS, AND THE LIKE Filed May 9, 1935 2Sheets-Sheet 1 fi .ww. .m m h m E. W n flh m 3imi- I I m W xx? 0 u a: W,1 m 6 Z f w w I ii 1h 0 o a W 6 April 1937- R. H. DRAEGE? El AL2,076,552

PROJECTORS, AND THE LIKE AUTOMATIC FOCUSING DEVICE FOR COPYING CAMERAS,

Filed May 9, 1955 2 Sheets-Sheet 2 Patented Apr. 13, 1937 UNITED STATESPATENT OFFICE Rupert H. Draeger, U. S. Navy, and Harold F. Bennett,Washington, D. 0.

Application May 9, 1935, Serial No. 20,611

8 Claims.

This invention relates to an automatic focusing device especiallyintended for use on a copying camera or projector or other apparatuswherein the distance may be varied between an object and the imageprojected by the lens and wherein it is desired to maintain the imagecontinuously in proper'focus as the size of the image is varied.

More particularly, this invention is intended 'to be used on a copyingcamera, or an enlarging camera, which is mounted for relative movementon a support and wherein an object which is to be copied or photographedby the camera may be of any size between finite limits, the object beinglocated at the base or end ofthe support. With this invention the lensof the camera will automatically be kept in properly focused relation tothe object being copied or photographed and the photo-sensitive surfaceas the camera is moved back or forth relative to the object so that thecamera may be placed at a proper distance from the object to permit theentire object to be photographed on the film or paper being used. Incopying books, for instance, the-size of the page being copied will varyaccording to the size of the books, thus, some books which are small orpocket size and other books which are large, such as unabridgeddictionaries, encyclopedias and the like all may be accommodated. Inphotographing a larger object a larger image would be focused on thefilm or photographic paper. To cause the image to be properly confinedon the film or photographic paper it is therefore necessary to move thecamera relative to the object being photographed. -As the camera ismoved to bring the image to the desired size the focus must beprogressively changed; otherwise, the image will not be focused properlyon the film or photographic paper.

This feature is particularly advantageous when photographing to adefinite scale or size.

The motion of the lens relative to the camera is not in constant ratioto the motion of the camera relative to the object to be photographed,

but when the camera is nearer the object the lens not only is fartherfrom the film but also has a more rapid motion relative to the movementof the camera in accordance with optical laws well known in the art.

This type of motion is obtained by means of a gear train and a slide armoffset from its pivot point and constituting part of a lever of whichthe other arm transmits the motion to the lens draw tube.

With this invention the act of changing the distance from the camera tothe object to be (Granted under the act of March 3, amended April 30,1928; 370 0.

1883, as G. 757) photographed automatically and simultaneously changesthe distance between the lens and the photographic film or paper. Forcertain purposes it may be desirable to substitute a lens having adifferent focal length. To permit this, the gear train is provided witha gear shift mechanism so as to provide a predetermined ratio ofmovement in the gear train to properly compensate for the new lens ofthe diiferent focal length. Obviously, any part of the gear train may'bechanged to provide. for diiferent lenses of different focal lengths, butone feature of this invention is the provision of a gear shift builtinto the gear train, permitting use of lenses for two predeterminedfocal lengths, but a gearshift may be provided permitting any desirednumber of different lenses.

With the foregoing and other objects in view, as will hereinafter becomeapparent, this invention comprises a combination and constructionhereinafter disclosed, claimed and illustrated on the accompanyingdrawings, wherein:

Fig. 1 -is a side elevation view of a copying camera to which thisinvention has been applied;

Fig. 2 is an enlarged sectional view through the camera supporting armand cameracase, the camera having been rotated at 90 relative to theshowing in Fig. 1; 4

Fig. 3 is a sectional view on line 3-3 of Fig. 1;

Fig. 4 is a sectional view on line H of Fig. 2; and

Fig. 5 is a view of the connection between the screw and lever taken online 5-5 of Fig. 2.

There is shown at it a table or surface on which an object H such as abook, held open by fiat glass i2, is placed for being photographed orcopied by the camera II. This camera i. is secured in a yoke l5depending from asupporting arm IS. The supporting arm l6 also carries afilm magazine l8 for supplying film in a conventional manner to thecamera I. The pedestal i'i carries a clamp for holding magazine tocamera case ll. Extending from the table I0 is a support rod IS, a gearrack 20 being formed in one side thereof. The supporting arm i6 isprovided with a bifurcated end 2! through which extends the thumb screws22, the bifurcated end 2| encompassing the support rod is. By looseningthe thumb screws 22 the supporting arm l6 may be moved to any positionalong the length of the support rod i9, and held there by tightening thethumb screws 22. Journaled within the supporting arm I6 is a shaft 23 onwhich is keyed a spur gear 24- enmeshed with the gear rack 20.

A door 25 in one side of the supporting arm l5 permits access to thisgear 24 for assembly purposes. Keyed to the shaft I a bevel gear 26which will partake of the rotation of the 5 spur gear 24. Meshing withthis bevel gear 25 is a bevel gear 21 keyed to one end of a shaft 28extending through the support arm IS. The other end of the shaft 28 isprovided with a miter gear 29 enmeshing with another miter gear 80 keyedon the end of a shaft 3|. Access to the miter gears 29 and 30 may be hadwhen necessary through the plug 32'. The shaft 3| is journaled throughthe stem 32 of the yoke I5 and terminated in a spur gear 33 within thecamera H. The yoke I5 is held to the supporting arm i6 by means of aslot 34 extending at least 90 or more about the stem 32 and a set screw35 extending through the end of the supporting arm it into the slot 34,holds the yoke i5 and camera M in proper relation to the supporting armit but permits such rotation of the camera as may be desired. The spurgear 33 meshes with an idler gear 36 which, in turn, meshes with a spurgear 31 keyed on a shaft 38, another but smaller gear 39 being likewisekeyed on this same shaft 38.

Extending through the yoke l5 is a gear shift arm 40 which is providedwith two spur gears 4| and 42. The larger spur gear 42 in one positionadapted to mesh with the spur gear 39 or when in shifted position thesmaller spur gear 4| being adapted to mesh with the larger spur gear 31on shaft 38, thus providing for a change in the gear ratio. Obviously,provision might be made for additional gear changes by providingadditional gears. A spring pressed plunger 48 and spring 44, held inposition by plug 45, serves to hold the gear shift arm in either of itsshifted positions. The lower end of this gear 40 arm 40 is provided withkeyed sleeve 46 into which extends upper splined end of a screw 41.Threaded on the screw 41 is a nut 48 which is held against rotation bymeans of the ways 45. As the nut 48 is caused to travel up or down thescrew 41, it moves an arm 50 of lever 5| fulcrumed on the shaft 52 inthe camera 4. This arm 50 is, in effect, a straight cam but may beoffset from fulcrum 52 as shown, and as the arm 50 moves lever 5| aboutits fulcrum 52 it 50 causes its other arm 53 to move the lens draw tube54 by means of a pin 55 extending through slot 56 in the lens barrel 51,the arm 53 ending in bifurcations 58 encompassing the pin 55.

The ratio of the gear train between the gear 55 rack 20 and the movementof the lens draw tube 54 is so chosen that as the supporting arm I6 ismoved up or down the supporting rod IS, the lens draw tube 54 will bemoved in the same direction up or down but in a proper modified 60 ratioso that the lens 58 will be at the proper focal distance between theobject II and the photographic film or paper 59. When a lens of adifferent focal length is substituted for the lens 58', the gear shift40 is operated so as to disengage the spur gears 42 and 58 and engagethe spur gears 4| and 31. Obviously, if a lens of yet a diiferent focallength is to replace the lens 58', then a different size gear may besubstituted somewhere along the gear train. The

arm 50 of the lever 5| slidably engages the nut 48 by passing through ashaftway 80, pivoted as at 6| to the nut 48, any other equivalentmechanical means being serviceable for this purpose.

In operation the camera :4 and supporting which is arm IE will be movedalong the rod l9 so as to be at the proper distance from the object H orbook being copied. If a different sized book or object of a differentsize is substituted for the object II, it will be necessary to move thecamera |4 relative thereto so as to cause the proper size image to befocused on the film 59. As the camera is thus moved the gear train fromthe rack 20 to the lens tube 54 operates automatically to maintain thelens 58 in substantially proper focus between the new object and thephotographic film or paper 59.

In practice it is frequently desirable and advantageous to make thefirst copy or negative merely a miniature and subsequently with thesame, or similar, apparatus, reproduce this picture in any desirablesize or sizes. However, the negative may be of any size relative to itsoriginal, and the subsequent copies may be of any size relative to thenegative.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

What is claimed is:

1. An automatic focusing device for a camera comprising an arm forsupporting the camera, means securing the camera to said supporting arm,a support rod, said arm being slidably securable along said support rod,a. gear rack on said support rod, a lens draw tube movablymounted insaid camera, and a gear train, one end of said gear train being in meshwith said support rod gear rack and the other end of said gear trainbeing so connected as to impart modified movement to said lens tuberelative to the camera, said gear train passing through the rotatableconnection between the camera and the supporting arm.

2. An automatic focusing device for a camera comprising an arm forsupporting the camera, a support rod, said arm being slidably securablealong said support rod, a gear rack on said support rod, 9. lens drawtube movably mounted in said camera, and a gear train, one end of saidgear train being in mesh with said support rod gear rack and the otherend of said gear train being so connected as to impart modified movementto said lens tube relative to the camera, said camera being rotatablysecured to said supporting arm by a stem extending from a yoke, saidstem having a hole extending therethrough and means extending throughsaid hole, connecting portions of the gear train.

3. An automatic focusing device for a camera comprising an arm forsupporting the copying camera, a support rod, said arm being slidably'securable along said support rod, a gear rack on said support rod, 9.lens draw tube movably mounted in said camera, and a gear train, one endof said gear train being in mesh with said support rod gear rack and theother end of said gear train being so connected as to impart modifiedmovement to said lens tube relative to the camera, gear shift means insaid gear train for changing the ratio of movement of the lens draw tubeto the movement of the supporting arm on the supporting rod to permitsubstitution of a lens of different focal length.

4. An automatic focusing device for a camera comprising an arm forsupporting the copying camera, a support rod, said arm being slidablysecurable along said support rod, a gearrack on said support rod, 2.lens draw tube movably mounted in said camera, and a gear train, one

end of said gear train being in mesh with said support rod gear rack andthe other end of said gear train being so connected as to impartmodified movement to said lens tube relative to the camera, said geartrain including a screw rotat-able thereby, a lever fulcrumed in thecamera.

case, one arm of the lever being connected to the lens draw tube and theother arm of the lever being engaged by a nut movable by rotation ofsaid gear train screw.

5. An automatic focusing device for a camera comprising an arm forsupporting the copying camera, a support rod, said arm being slidablysecurable along said support rod, a gear rack on said support rod, alens draw tube movably securable along said support rod, a draw tubelens barrel slidably arranged on said camera, means for rotatablysecuring said camera on said arm,

0 means for slidably adjusting said draw tube lens barrel and extendingthrough the camera into said support arm along the axis of rotation ofthe camera, and means for automatically actuating said adjusting meansupon movement of the arm along the support rod,

. 7. An automatic focusing camera comprisinga. light-tight casing, anarm for supporting the camera, a support rod, said arm being slidablysecurable along said support rod, a draw tube lens barrel on saidcamera, means for adjusting said draw tube lens barrel, a. gear trainextending through the said camera into said support arm and adapted toactuate said adjusting means, and means for automatically operatingsaid. gear train upon movement of the arm along said support rod.

8. An automatic focusing camera comprising a. light-tight casing, an armfor supporting the camera, a support rod, said arm being slidablysecurable along said support rod, a draw tube lens barrel slidablyarranged on said camera, a gear train and bell crank to said draw tubeextending through said camera into said support arm, means forautomatically operating said gear train and bell crank, one arm of saidbell crank being pivotally connected with the draw tube lens barrel, andthe other arm being adapted to be pivoted about the fulcrum of the bellcrank by the train of gears.

RUPERT H. DRAEGER. HAROLD F. BENNETT.

